Lecture 8: Web Commerce Technologies

Hidden Fields

A hidden field within an HTML form is the simplest way to do session management. A hidden field is like any other INPUT FORM entity; it is simply not displayed by the browser. It can be inspected using, for example, the "View Source" option of the browser, where it will look something like: <input type="hidden" name="SID" value="XYZZY8765765vk5ht">.

Submission of this FORM to the specified server will contain the name=value pair from the hidden field along with the data from any other (non-empty) INPUT elements.
The server-side program which processes the FORM at the server will normally return the same hidden field back to the browser.

Whilst hidden fields are a simple technique for state maintenance, they are not a general solution, since they only work in the context of a sequence of FORM submissions. For more generic applications, another technology is needed.

previous | start | next